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Main Boards => PowWow => Topic started by: WDELongbow on November 07, 2023, 10:57:09 AM

Title: Assessing Safety of Vertical Limb Stress Lines
Post by: WDELongbow on November 07, 2023, 10:57:09 AM

I saw a vintage recurve online (an auction site) that interested me. I'm curious as to how to assess/judge vertical stress lines in a vintage laminated recurve limbs. I know it's common for laminated limbs to have a few faint vertical stress lines, and seems to be no big deal. But in this case there are significant, highly visible vertical stress lines in the fadeout region of limbs, on back and belly side. Bow is "online", so I can't do a hands-on inspection at this time - such as running a cotton ball along limb to detect a splinter.

This is a higher end target recurve (38 lbs draw) that is a few decades old.

Here's what I'd like to know ... Would it be reasonably safe to shoot a bow like this? Or should a bow in this condition be avoided all together.

Title: Re: Assessing Safety of Vertical Limb Stress Lines
Post by: Steelhead on November 07, 2023, 08:54:16 PM

Alot of guys shoot vintage bows like that.I have had a few and shot them.keep an eye on it

You can saturate the cracks with thin superglue.It will seep into them kinda like water.

Title: Re: Assessing Safety of Vertical Limb Stress Lines
Post by: WDELongbow on November 08, 2023, 12:20:21 AM

Thanks Steelhead!

Title: Re: Assessing Safety of Vertical Limb Stress Lines
Post by: LoneRanger on November 08, 2023, 07:48:21 AM

My Dad has a bow, an older Black Widow, with a vertical crack in the glass. He put a little dot with a Sharpie at the top of the crack to monitor if it grows, which it hasn’t in years. He shoots the bow as his primary bow.

Title: Re: Assessing Safety of Vertical Limb Stress Lines
Post by: WDELongbow on November 08, 2023, 02:01:47 PM

Very practical solution - Sharpie mark. Appreciate the tip.

Title: Re: Assessing Safety of Vertical Limb Stress Lines
Post by: Hud on November 08, 2023, 05:54:50 PM

I have had a number of Bear bows built prior to mid 1960's with stress lines. Early fiberglass was primarily longitudinal glass that developed lines. They are easy to spot in white glass. I have used Locktite 420, it is very strong and thin. To limit the amount coming out, I have used a tooth pick (round with double points) to guide a drop while holding the bow at a slight angle so it runs down the stress line. Put a drop at a time on the toothpick.  You might clean the surface with lacquer thinner first and put some wax paper on your work surface to catch any spills. If you put too much on, it almost easier to whip it with a thinner (see link), than trying to sand it off after it dries. If you want to experiment, use a glass, coffee cup, or dish with a crack.

https://www.google.com/search?q=Locktite+420&rlz=1C1PQHA_enUS539US565&oq=Locktite+420&gs_lcrp=EgZjaHJvbWUyBggAEEUYOTIJCAEQABgKGIAEMgkIAhAAGAoYgAQyCQgDEAAYChiABDIJCAQQABgKGIAEMgkIBRAAGAoYgAQyCQgGEAAYChiABDIJCAcQABgKGIAEMgkICBAAGAoYgAQyCQgJEAAYChiABNIBCjIxMTU4ajBqMTWoAgCwAgA&sourceid=chrome&ie=UTF-8